The T/S (Turn signal Switch) is located in the steering column, activated by the lever on the left side of the steering column.
The Flasher is located behind the instrument cluster. There are 2 flashers- one for the turn signals, one for the Emergency flasher. Either one is a PITA to get to. They are identical in function & appearance, but are separate circuits.
You MAY get lucky and not have to replace the T/S Flasher. It will depend on the current draw, as the LED lamps draw far less current than the incandescent bulbs.
Just replace the old bulbs as you plan, and see if the turn signals work OK (flashing rate). If the turn signals flash too slowly (or not at all) you'll have to replace the T/S Flasher with one compatible with LED's.
Neil